Zoom lens
AssigneeFuji Photo Optical Co., Ltd.
InventorAkiko Nagahara
Life of this patent
Estimating the term…
Abstract
A zoom lens having a maximum of thirteen lens elements in four lens groups, the four lens groups being of negative, positive, positive, and positive refractive power, in order from the object side. The first lens group G1 and the fourth lens group G4, in order from the object side, are fixed in position relative to the image surface of the zoom lens, and the second lens group G2 and the third lens group G3 move with a mutual relationship for continuous zooming and correction for what would otherwise be a shifting of the image surface of the zoom lens with zooming. Further, certain conditions are preferably satisfied in order to provide a zoom lens that is compact, yet provides a bright image with well-corrected aberrations.
Claims15
A zoom lens comprising, in sequential order from the object side:
- a first lens group having negative refractive power and that is fixed in position during zooming;
- a second lens group having positive refractive power;
- a third lens group having positive refractive power;
- and
- a fourth lens group having positive refractive power that is fixed in position during zooming;
- wherein, the second lens group and the third lens group move in a mutual relationship for continuous zooming and correction for what otherwise would be a shifting of the image plane caused by zooming, and
- the following Condition is satisfied
- β2×β3>−2.2
- where
- β2 is the lateral magnification of the second lens group at the wide-angle end for an object at infinity, and
- β3 is the lateral magnification of the third lens group at the wide-angle end for an object at infinity.
Dependencies are inferred from the claim text.